This invention relates to cooling fans for electric motors and generators and more particularly to improved rotor and end connectors for induction motors having precisely shaped fan blades to maximize ventilation efficiency, without diminishing the strength of the blades.
Dynamoelectric machines, particularly high speed induction electric motors, produce a lot of heat, particularly in the rotor winding and the laminations of steel that make up the body of the rotor. Various attempts have been made to provide ventilation at one end of the rotor using radial fan blades. For example, in U.S. Pat. No. 821,249 (Lundell), the patentee states that he attempts to improve ventilation of a dynamoelectric machine by providing end plates having web-like arms which appear to force air through a flange to cool the winding.
According to U.S. Pat. No. 1,628,086 (Warner), the patentee includes a fan in an electric motor. The fan appears to force air around one end of the coils in order to cool the motor coils and field laminations.
Similarly, the patentee of U.S. Pat. No. 3,075,106 (Chi) states that he uses an improved rotor to cool a hermetic refrigeration motor-compressor unit. According to the patentee, the rotor has a plurality of impeller blades at each end, with the outer portion of each blade leading the inlet portion in the direction of rotation of the rotor. The patentee also states that the impeller blades direct refrigerant cooling fluid into contact with the winding end turns to transfer heat away from the motor.
None of the foregoing attempts, however, appears to provide a satisfactory solution to the problem of providing a suitable cooling fan for an induction motor.